The ultimate goal of this proposal is to reduce prescription opioid related overdoses and deaths. The U.S. Congress, the National Institute on Drug Abuse, and the Centers for Disease Control and Prevention have identified prescription opioid abuse as a top public health problem. The 14,800 prescription opioid-related overdose deaths reported in 2008 have increased five-fold since 1999 and far surpass overdose deaths from cocaine and heroin. Emergency departments (ED) are the source of 39% of prescriptions for controlled substances and represent particularly high risk settings for doctor shopping and drug diversion. Contributing factors include the episodic and time-pressured nature of emergency care, lack of a long-term physician- patient relationship, and until recently, the absence of integrated data systems about prior controlled substance use. Prescription monitoring programs (PMPs) are statewide pharmacy databases designed to limit drug misuse by providing data on controlled medication dispensing. Despite the considerable expense of PMPs, the data on their impact to reduce opioid related harms are limited. A major challenge to the effectiveness and evaluation of PMPs is low rates of physician adoption; less than 6% of eligible providers will register for PMP access in the first year of operation. Washington State recently mandated that ED providers register for PMP access by July 2012; all 87 eligible hospitals have met this requirement. Although the policy does not require PMP use, it does create universal provider PMP access in a high risk setting. We capitalize on this opportunity to study a critical public health question: Does PMP use in emergency departments reduce opioid prescribing, overdoses, and deaths? In collaboration with the Washington State Health Care Authority and the Washington State Prescription Monitoring Program, we will create a unique dataset linking provider PMP use, opioid prescribing, and outcomes to accomplish the following Aims: Specific Aim 1. Identify predictors of PMP use by emergency department providers Specific Aim 2. Assess the impact of emergency department PMP use on total, inappropriate, and appropriate opioid prescribing Specific Aim 3. Assess the impact of emergency department PMP use on patient outcomes. To achieve these Aims, we will create a unique dataset of 2,400 providers and 1.4 million ED visits that links provider PMP use to patient claims and mortality files. Our proposal will result in novel and policy-relevant knowledge to address the public health epidemic of prescription opioid abuse.